Method of Making A Top Stack Linkage With an Injection Molded Magnesium Link

ABSTRACT

A link of a top stack linkage for a convertible top of a vehicle is presented for immediate incorporation in a top stack linkage. The link is molded as a spine having a main body portion and an offset portion, and one or more lateral structural members including at least one reinforcing rib. The molding forms a unitary pivot link, installed in the top stack linkage as molded, to reduce finishing of the parts, and reducing fabrication time and linkage weight from known top stack linkage configurations. A method of manufacturing includes providing a mold defining an interior cavity that defines the shape of a pivot link, injecting molten magnesium into the mold, and molding the molten magnesium to form a spine and at least one of a plurality of lateral structural members that form a monolithic pivot link.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a division of U.S. application Ser. No. 12/252,102filed Oct. 15, 2008, which, in turn, claims the benefit of U.S.provisional Application No. 60/979,922 filed Oct. 15, 2007, thedisclosures of which are incorporated in their entirety by referenceherein.

BACKGROUND

1. Field of the Invention

The present invention relates to a link for an articulated linkage, suchas a convertible top stack linkage, that is formed by injection moldingmagnesium to form a link with integral reinforcing ribs, integral pivotpins and integral bushings.

2. Background

Vehicles may be provided with roofs that are movable between an extendedposition and a retracted position, such as convertible tops andretractable hardtops. These types of vehicle roofs are generallyconstructed to be moved between the extended and retracted position onan articulated linkage that is commonly referred to as a top stacklinkage. It has previously been proposed in the Applicant's assignee'sPCT application Serial No. PCT/US2005/006522, filed Feb. 28, 2005 toform parts of the bows and rails of the top stack with an injectionmolded magnesium forming process. The prior application disclosed theuse of stamped metal links to interconnect the side rails and bows ofthe top stack. Some of the links also incorporated tubular portions thatwere formed into required shapes and provided with end fittings tosecure the links to the side rail, other links and bows.

SUMMARY

One aspect of the present invention is to provide an operational link ofa top stack linkage for a convertible top of a vehicle. The linkincludes a spine extending through a length and a width of the link andmay have a first side and a second side. The spine may have a main bodyportion and an offset portion. The offset portion is offset relative tothe main body portion. The link further includes a plurality ofreinforcing ribs integrally molded to the spine and extending from atleast one of a first side or a second side of the link. The plurality ofreinforcing ribs may also extend through the length and width of thespine. In one embodiment, the plurality of reinforcing ribs may extendfrom both the first and the second side of the link. The operationallink further includes a plurality of lateral structural membersintegrally molded with the spine. The spine, the plurality ofreinforcing ribs, and the lateral structural members may form a singleand unitary link.

In some embodiments, the link may have a front portion and a backportion that define planar flange portions of the pivot link. The frontportion and the back portion may lack reinforcing ribs

In other embodiments, the plurality of lateral structural members of theoperation link may include a plurality of bushings. At least one of theplurality of bushings may include a plurality of radially extending ribsinterconnected by a circumferentially extending rib for reinforcing theat least one bushing.

In other embodiments, the plurality of lateral members of theoperational link may include a peripheral wall and a plurality ofintegral pins. As such, the operation link may further include a pivotflange extending outwardly from the peripheral wall. The pivot flangemay support at least one of the plurality of integral pins. Theplurality of lateral structural members may include a plurality of ribsextending vertically from the link which reinforce the pivot flange. Theperipheral wall may have one or more attachments secured to theperipheral wall by a fastener. For example, the one or more attachmentsmay be a top support strap and the fastener may be a threaded fastener,rivet, or pin. The peripheral wall may have a fastener receptacle holefor securing the fastener to the peripheral wall.

Another aspect of the present invention provides for a method ofmanufacturing a link of a top stack linkage for a convertible top of avehicle. The method includes providing a mold defining an interiorcavity that defines the shape of a pivot link. The method furtherincludes injecting molten magnesium into the mold. The method furtherincludes molding the magnesium injected mold to form a spine. The spinemay have a plurality of lateral structural members that are integrallymolded with the spine to form a single and unitary link. In oneembodiment, the spine has a main body portion and at least one offsetportion that is not coplanar relative to the main body portion.

In some embodiments, the plurality lateral structural members mayinclude a plurality of reinforcing ribs. Accordingly, the method mayfurther include molding the plurality of reinforcing ribs to reinforcethe pivot link and maintain a spatial orientation of the offset portionrelative to the main body portion.

In other embodiments, the pivot link may include a front portion and aback portion that define planar flange portions of the pivot link.Accordingly, the molding step may further include forming the planarflange portions for permitting a plurality of adjacent links to pivotrelative to the pivot link.

In other embodiments, the plurality of lateral structural members mayinclude a plurality of pins disposed at spaced locations on the spine.Accordingly, the method may further include connecting a plurality oflinks and a plurality of bows to the pivot link.

In other embodiments, the plurality of lateral structural members mayinclude a plurality of bushings disposed at spaced locations on thespine. The plurality of bushings may be reinforced by a plurality ofradially extending ribs interconnected by circumferentially extendingribs. Accordingly, the method may further include inserting a pluralityof pins in the plurality of bushings for connecting adjacent links tothe pivot link.

Another aspect of the present invention provides for an operational linkof a top stack linkage for a convertible top of a vehicle. The operationlink includes a spine extending through a length and a width of thelink. The link may have a first side and a second side. The spine mayalso have a main body portion and an offset portion. The offset portionis offset relative to the main body portion. The operation link furtherincludes a plurality of reinforcing ribs extending from at least one ofthe first side or second side of the link. The reinforcing ribs mayfurther extend through a length and width of the spine. In oneembodiment, the plurality of reinforcing ribs may be varied in length.

The operation link further includes a plurality of pins integral withthe spine. The pins may be disposed at spaced locations on the spine forsecuring a plurality of other links and bows to the link. The operationlink further includes a plurality of bushings integral with and disposedat spaced locations on the spine for connecting the link to a pluralityof other links. The plurality of bushings may be reinforced by aplurality of radially extending ribs interconnected by circumferentiallyextending ribs. The operation link further includes an interiorreceptacle boss located at the offset portion of the spine. The boss maybe supported about its periphery by a plurality of reinforcing ribs. Theoperational link further includes a peripheral wall substantiallyextending around the periphery of the link. The spine, the plurality ofreinforcing ribs, the plurality of pins, the plurality of bushings, theinterior receptacle boss, and the peripheral wall may be formed as asingle and unitary pivot link.

These and other aspects of the present invention will be betterunderstood in view of the attached drawings and following detaileddescription of the invention.

BRIEF DESCRIPTION OF THE DRAWINGS

The features of the present invention which are believed to be novel areset forth with particularity in the appended claims. The presentinvention, both as to its organization and manner of operation, togetherwith further object and advantages thereof, may best be understood withreference to the following description, taken in connection with theaccompanying drawings, which:

FIG. 1 is a side elevation view of a prior art convertible top and topstack linkage made with fabricated operational links;

FIG. 2 is a perspective view of a prior art pivot link that is stamped,machined and assembled in accordance with a prior art manufacturingmethod;

FIG. 3 is a side elevation view of a control link made according to oneembodiment of the present invention;

FIG. 4 is a perspective view of the control link made according to oneembodiment of the present invention;

FIG. 5 is an inverted perspective view of the control link madeaccording to one embodiment of the present invention;

FIG. 6 is a cross-sectional view taken along the plane of section ofline 6-6 in FIG. 3;

FIG. 7 is a cross-sectional view taken along the line of section of line7-7 in FIGS. 3; and

FIG. 8 is a cross-sectional view taken along the plane of section ofline 8-8 in FIG. 3.

DETAILED DESCRIPTION

As required, detailed embodiments of the present invention are disclosedherein; however, it is to be understood that the disclosed embodimentsare merely exemplary of the invention that may be embodied in variousand alternative forms. The figures are not necessarily to scale; somefeatures may be exaggerated or minimized to show details of particularcomponents. Therefore, specific structural and functional detailsdisclosed herein are not to be interpreted as limiting, but merely as arepresentative basis for teaching one skilled in the art to variouslyemploy the present invention.

By way of background, the top stack linkage disclosed in Applicant'sprior co-pending application will be generally described. Referring toFIG. 1, a convertible top 10 is illustrated, including a top stack 12.The convertible top 10 includes a one bow 14 that is adapted to besecured to a windshield header 16. Moving rearwardly from the one bow,the other bows of the top stack 12 are identified as a two bow 18, athree bow 20, a four bow 22 and a five bow 24. The bows support a topcover 26 and extend transversely relative to the vehicle when theconvertible top 10 is in its extended position. The two bow 18, threebow 20 and four bow 22 are assemblies including extruded portions andinjection molded magnesium portions. The one bow 14 is integrally formedwith the front rail (not shown) which is connected to a center rail 32.The center rail 32 is articulately connected to rear rail 34. The onebow 14, front rail, side rail 32 and rear rail 34 all may be formed asinjection molded magnesium parts. The rails define a portion of theperimeter of the convertible top with the top cover fabric being securedto the rail to provide a tight fitting convertible top.

In the prior implementation of this convertible top, it was believed tobe necessary to form the operational links of the top stack as eitherstamped parts or formed tubular parts to obtain parts having the desireddurability in a cost-effective manner. For example, the control link 36,pivot link 40, pressure link 42 and balance link 44 were all previouslyformed with either a metal stamping operation or tube forming andwelding process. The cost associated required for stamping steel plate,hydroforming tubular members and welding adds to the cost of the parts.Also, the pivot points in many instances required machining operationsand separate bushings that also added to the cost of the entireassembly. Assembling the parts together with separate pins requiredcareful alignment of the pins and an intricate assembly procedure. Closetolerances must be met to provide a top stack linkage that can bereliably and repeatedly assembled without complications resulting fromtolerance stack up.

Referring to FIG. 2, a perspective view of the pivot link 40 isprovided. The prior art pivot link is a complicated part that iscritical to operation of the top. The pivot link 40 has a main bodyportion 46 that is generally formed to lie in a single plane. An offsetportion 48 is offset from the plane of the main body portion 46. A pivotpin 50 is provided for connecting the front end of the pivot link to thecontrol link 36. A tubular receptacle 52 is provided on the pivot link40 that receives a fastener (not shown) for connecting the control linkto the rear rail 34. A pin 54 is secured to the rear portion of thepivot link 40 which connects the pivot link 40 to the pressure link 42.In addition, a three bow opening 56 and four bow opening 58 are providedon the pivot link 40 for attachment to the three bow 20 and four bow 22,respectively. To assure proper operation of the top 10, five connectionpoints on the pivot link 40 must conform to closely held tolerances. Toassure such close tolerances, the orientation of the main body portion46 relative to the offset portion 48 must be precisely aligned wheninitially manufactured. Through use, stamped parts and formed tubularmembers may be bent if the top is impacted by a foreign object, eitherfrom a source external to the vehicle or in the course of extending orretracting the convertible top. Any distortion of the formed part maycomplicate, or interfere with, proper operation of the top 10. Thepresent invention is directed to overcoming the problems identifiedabove in regard to the prior top, and more specifically, with regard tothe operational links thereof.

Referring to FIGS. 3-5, a monolithic pivot link 100 is illustrated as anexample of an operational link of a top stack linkage that may be madein accordance with the present invention. It should be understood thatother operational links, including, but not limited to the links thatwould replace the prior art pressure link 42, balance link 44 and otheroperational links, may be manufactured including various combinations ofthe structural elements of the monolithic pivot link 100. The pivot link100 includes a spine 102 in the form of a wall that extends through thelength and width of a substantial portion of the pivot link 100 as shownin FIGS. 3-5 and 6-8 at the end of the lead line for spine 102. Aplurality of reinforcing ribs 104 extend from one or both sides of thewall extending through a substantial portion of the pivot link 100. Thelength, thickness, shape and orientation of the reinforcing ribs 104 maybe varied depending upon the structural requirements of the pivot link100. These parameters may be varied depending upon the space availablewithin the top stack linkage structure to allow for clearance ofrelatively movable parts of the top stack linkage. Planar flangeportions 106 may be provided as required to permit adjacent links topivot relative to the pivot link 100. Such planar portions 106 may beprovided where no reinforcing ribs are required in the planar flangeportions 106.

Integral pins 108 may be provided at desired locations where other linksand bows are secured to pivot link 100. The integral pins 108 are formedto net size and shape in precisely located positions to assure easyassembly and smooth operation of connected parts.

Integral bushings 110 may be formed on the pivot link 100 at desiredlocations to receive pins that connect the pivot link 100 to adjacentlinks and supporting structures. Integral bushings 110 are formed to netsize and shape at desired locations precisely and without need foradditional machining or surface finishing to provide a finished partbecause the pivot link 100 is formed of magnesium in an injectionmolding process.

With particular reference to FIG. 4 and continued reference to FIGS. 3and 5, one of the integral bushings 110 is shown to include a pluralityof radially extending ribs 116 that are interconnected by acircumferentially extending rib 118. The radially extending ribs 116 andcircumferentially extending rib 118 reinforce the integral bushing 110.

A pivot flange 120 supports integral pin 108. The pivot flange 120 isreinforced by triangular ribs 122. The triangular ribs 122 reinforce theopposite side of the pivot flange 120 from the pin 108. The pivot flange120 extends outwardly from a peripheral wall 124 of the pivot link 100.

The peripheral wall 124 extends substantially around the entireperiphery of the pivot link 100. The peripheral wall 124 providesadditional reinforcement and a smooth exterior for the pivot link 100.

An interior receptacle boss 128 is provided that is supported about itsperiphery by reinforcing ribs 104. The interior receptacle boss 128 willbe further described below with reference to FIG. 8.

The term “lateral structure members” as used in this disclosuregenerally refers to protrusions that extend laterally, or in thecross-car direction from the spine 102. Examples of lateral structuralmembers may include one or more of the following: reinforcing ribs 104,pins 108, bushings 110, radially extending ribs 116, circumferentiallyextending ribs 118, triangular ribs 122, peripheral wall 124, orreceptacle boss 128.

A top support strap 130 is shown in FIGS. 3 and 4. The top support strap130, or other types of attachments, may be secured to the peripheralwall 124 of the pivot link 100 by a fastener 132. The fastener 132 maybe a pin that is secured to the fastener receptacle hole 112. Thefastener 132 may be a threaded fastener, rivet or pin. The fastener 132may be secured within the fastener receptacle hole 112 by a press-onspring nut (not shown) to facilitate assembly.

With particular reference to FIG. 5 and continued reference to FIGS. 3and 4, the monolithic pivot link 100 may include a main body portion 136of the spine 102. In addition, an offset portion 138 of the spine 102may be provided as part of the pivot link 100. The offset portion 138 isdisposed in a plane that is offset relative to the plane of the mainbody portion 136. Multiple offset portions 138 may be provided along thespine 102. The reinforcing ribs 104 function to reinforce the pivot linkand also maintain the spatial orientation of the offset portion 138relative to the main body portion 136.

Referring to FIG. 6, a section is taken through the main body portion136. An integral pin 108 is shown extending from a planar flange portion106. In addition, reinforcing ribs 104 are shown extending from one sideof the main body portion 136. The reinforcing ribs 104 may extend fromthe spine 102 to a varying extent as required to locally reinforce thespine 102. The integral bushing 110 shown in FIG. 6 is reinforced byradially extending ribs 116 that serve to reinforce and fix the positionof the inner bushing 110.

Referring to FIG. 7, a different section is taken through the pivot link100 in the main body portion 136 of the spine 102. The reinforcing rib104 is shown on the left side of FIG. 7 that is substantially longerthan the reinforcing rib shown on the right side of FIG. 7. The abilityto vary the length of the reinforcing ribs 104 permits reinforcement ofthe spine 102 to a greater or lesser extent depending upon the clearanceavailable on either side of the spine 102. The peripheral wall 124 isalso shown in FIG. 7 which reinforces the periphery of the spine 102.

Referring to FIG. 8, a section is taken through the offset portion 138of the spine 102 of the link 100. An interior receptacle boss 128 isshown that is supported by reinforcing ribs 104. The interior receptacleboss 128 provides a blind opening in one side of the pivot link 100 inwhich a screw or other fastener may be secured. A reinforcing rib 104may be provided on the opposite side of the spine 102 from the interiorreceptacle boss 128. The peripheral wall 124 reinforces the spine in theoffset portion 138 on both sides of the interior receptacle boss 128.

The monolithic pivot link 100 is formed in an injection molding processin which molten magnesium is injected into a mold. The mold defines aninterior cavity corresponding precisely to the net size and shape of thepivot link 100. The injection molding process permits the spine 102,including its main body portion 136 and offset portion 138, to be moldedin a single step. Reinforcing ribs 104, planar flange portions 106,integral pins 108, and integral bushings are also formed as a singlepart that is integral with the spine 102. Fastener receptacle holes 112may be formed without the need to drill or machine the pivot link afterthe molding step.

The manufacturing process may be applied to other operational links, aspreviously indicated, with design flexibility being obtained by definingthe required planes of the spine 102 and then reinforcing one or bothsides of the link using variable length reinforcing ribs. Joints in thelink may be provided in the form of bushing or pins that are integrallyformed on the link.

According to the magnesium injection molding process described herein, adurable and extensively reinforced operating link may be provided thathas precisely located pins, bushings and other connection points thatrequire no machining. The link made according to the process results insubstantial cost savings as a result of reducing the number of parts andmanufacturing steps required to provide a robust link that may beadapted to a wide variety of link designs.

While exemplary embodiments are described above, it is not intended thatthese embodiments describe all possible forms of the invention. Rather,the words used in the specification are words of description rather thanlimitation, and it is understood that various changes may be madewithout departing from the spirit and scope of the invention.Additionally, the features of various implementing embodiments may becombined to form further embodiments of the invention.

1. A method of manufacturing a pivot link of a top stack linkage for aconvertible top of a vehicle, the method comprising: providing a molddefining an interior cavity that defines the shape of a pivot link;injecting molten magnesium into the mold; molding to form a monolithiclink; the magnesium injected into the mold to form a spine, and moldingto form a plurality of lateral structural members that are integral withthe spine to form a monolithic link.
 2. The method of claim 1 whereinthe molding step further comprises molding the spine to include a mainbody portion and at least one offset portion relative to a plane of themain body portion.
 3. The method of claim 1 wherein the lateralstructural members include a plurality of reinforcing ribs and themolding step further comprises molding the plurality of reinforcing ribsto reinforce the pivot link, the spatial orientation of the offsetportion relative to the main body portion.
 4. The method of claim 1wherein the pivot link includes a front portion and a back portion thatdefine planar flange portions of the pivot link and the molding stepfurther comprises forming the planar flange portions for permitting aplurality of adjacent links to pivot relative to the pivot link.
 5. Themethod of claim 1 wherein the plurality of lateral structural membersincludes a plurality of pins disposed at spaced locations on the spineand the method further comprises connecting a plurality of links and aplurality of bows to the pivot link.
 6. The method of claim 1 whereinthe plurality of lateral structural members includes a plurality ofbushings disposed at spaced locations on the spine, the plurality ofbushings being reinforced by a plurality of radially extending ribsinterconnected by circumferentially extending ribs, and the methodfurther comprises inserting a plurality of pins in the plurality ofbushings for connecting adjacent links to the pivot link.
 7. A method ofmanufacturing a top stack linkage with a molded pivot link for operatingthe top stack linkage for a convertible top of a vehicle, the methodcomprising: providing a mold defining an interior cavity that definesthe shape of a pivot link; injecting molten magnesium into the mold;molding to form a spine, molding to form a plurality of lateralstructural members that are integral with the spine to form a monolithiclink, and assembling the pivot link within the top stack linkage uponremoval from the interior cavity.
 8. The method of claim 7 wherein themolding step further comprises molding the spine to include a main bodyportion along a first plane and at least one offset portion offsetrelative to the first plane of the main body portion.
 9. The method ofclaim 7 wherein the lateral structural members include a plurality ofreinforcing ribs.
 10. The method of claim 7 wherein the molding stepfurther comprises molding the plurality of reinforcing ribs to reinforcethe spatial orientation of the spine offset portion relative to thespine main body portion.
 11. The method of claim 7 wherein the moldingstep further comprises forming at least one planar flange portion forpermitting a plurality of adjacent links in the top stack linkage topivot relative to the pivot link.
 12. The method of claim 7 wherein theplurality of lateral structural members includes molding a plurality ofpins disposed at spaced locations on the spine and further comprisesconnecting a plurality of links in the top stack linkage and a pluralityof bows in the top stack linkage to the pivot link.
 13. The method ofclaim 7 wherein the plurality of lateral structural members includesmolding a plurality of bushings disposed at spaced locations on thespine, the plurality of bushings being reinforced by molding a pluralityof radially extending ribs interconnected by circumferentially extendingribs, and further comprises inserting a plurality of pins in theplurality of bushings for connecting adjacent links in the top stacklinkage to the pivot link.